Conventionally, in manufacturing semiconductor devices, fine processing by lithography utilizing photoresists has been employed. The fine processing is a processing method includes forming a thin film of a photoresist on a semiconductor substrate such as a silicon wafer; irradiating the substrate with active light such as ultraviolet through a mask pattern having a pattern of semiconductor device; developing the substrate; and etching the substrate with the obtained photoresist pattern as a protection film. This forms fine concavities and convexities corresponding to the pattern on the surface of the substrate. In recent progress in high integration of semiconductor devices, shorter wavelength active light tends to be used, i.e., an ArF excimer laser beam (193 nm) and to EUV light (13.5 nm) have been taking the place of a KrF excimer laser beam (248 nm) to.
Thus, controlling profiles (resist shapes) and improving adhesion to substrates are required for resists more than before.
As an underlayer film between a semiconductor substrate and a photoresist, a film known as a hardmask that contains a metal element such as silicon has been used. In this case, the resist and the hardmask are significantly different in their components, and thus their removal rates at which the resist and the hardmask are removed by dry etching largely depend on gaseous species used for dry etching. By selecting proper gaseous species, the hardmask can be removed by dry etching without a significant decrease in the film thickness of the photoresist. A resist underlayer film has been thus placed between a semiconductor substrate and a photoresist in order to achieve a variety of effects in the manufacture of semiconductor devices in recent years (see Patent Documents 1 and 2).
Although compositions for resist underlayer films have been studied, development of novel materials for resist underlayer films are demanded to meet diverse properties that the resist underlayer film is required to have.